Add unwrap method to MoveItems to reclaim the Vector

[mahkoh]

impl MoveItems<T> {
    /// Drops all elements that have not yet been moved and returns the (now empty) vector
    /// that was used in the creation of `self` without performing any allocations.
    pub fn unwrap(self) -> Vec<T> {
        // ...
    }
}

[huonw]

(This would be O(n) in the worst/average case, since it would have to slide everything back to the start of the vector.)

[mahkoh]

Nothing gets moved since everything gets dropped.

[huonw]

Oh, right. EIther way, still O(n). :P

[mahkoh]

The only choices you currently have (drop it or iterate over it) are already O(n). Either way: The case I'm interested in is the one where all items have been moved.

[mahkoh]

But there are probably many cases where the user wants to retain the unmoved items and/or where a single memmove is faster than dropping everything. Maybe unwrap and unwrap_drop or unwrap_retain and unwrap. In the case where all items have been moved they are equivalent.